French-owned gas and electricity supplier EDF Energy has posted an increase in UK annual earnings to £1.69 billion last year, driven by the performance of its eight nuclear power stations.

The company, which unveiled a deal last year to build a new nuclear site at Hinkley Point C in Somerset, also confirmed that it expects to announce an extension in the life of its Dungeness B power station in Kent until 2028.

The results did not reveal the scale of profits from EDF's domestic supply business, which are expected to be published in June.

The division is likely to have remained loss-making in 2013, though narrower than the £92 million shortfall the year before.

EDF, which serves around 3.9 million households and is one of the so-called Big Six UK energy suppliers, raised its domestic tariffs by 3.9% from January, lower than many of its rivals.

Its total number of gas and electricity accounts is 5.7 million, a net increase of 250,000 in 2013 and 600,000 over the last three years.

The company said it had invested £1.1 billion on its existing nuclear and coal stations, its new nuclear project, new generation capacity, gas storage facilities and its customer supply business.

Underlying earnings rose 1.4% from £1.67 billion in 2012 to £1.69 billion in 2013. But on a like-for-like basis and excluding the impact of accounting revaluations, earnings were up 4.1%.

Chief executive Vincent de Rivaz said: "Our financial performance means we can make the big investments the country needs to give it the reliable low carbon energy it needs now and in the future. It also means we can invest in jobs and skills for the long term.

"The investment we are making in our existing nuclear power stations has resulted in their best performance for eight years.

"We believe that their operating lives can be safely extended and we expect to be able to announce a 10-year life extension for Dungeness B before the end of 2014.

"This means existing nuclear can hand over directly to the next generation of nuclear power stations without the need for more fossil fuel generation.

"Our customer numbers also continue to grow. We took early action to limit price rises and will continue to work closely with policy-makers to bear down on rising costs for consumers."

Group profits of 16.8 billion euros (£13.8 billion) were a 5.5% increase on 2012 on a like-for-like basis.